VO2 slow component is independent from critical power

The aim of this study was to determine whether the amplitude of the V˙O (2) slow component was dependent from Critical Power (CP; the slope of the linear time - distance relationship) in individuals matched for V˙O (2) peak. 30 moderately-trained endurance athletes completed a maximal graded exercise test, 2 randomly ordered constant power tests at 90 and 100% of peak power output (PPO), and 2 constant duration test of 6 min at 30% of the difference between CP and PPO. Afterwards, participants were ranked according to their relative CP (%PPO; a direct measure of aerobic endurance). The median third was excluded to form a low aerobic endurance group (LEG) and a high aerobic endurance group (HEG). A t-test revealed no difference between LEG and HEG in peak oxygen consumption, but a large difference in their relative CP (p<0.001, effect size=3.2). A' (2) was similar between groups (626 ± 96 and 512 ± 176 ml, corresponding to 26 ± 4 and 24 ± 8% of end exercise oxygen consumption, respectively; NS) and was not associated with relative CP (r=0.10; NS). These results suggest that increasing CP probably extends the range of exercise intensities over which the V˙O (2) slow component does not develop, but does not decrease the amplitude of this phenomenon once it occurs.